I think you've confused electric power steering with steer by wire. None of those cars are steer by wire. As far as I know no one sells a consumer vehicle with steer by wire, yet. It's in some things like forklifts and tractors. It's certainly being worked on.

I assumed from motoring shows on the TV which talk about 'sneeze' zones in the center of performance car steering that this must be implemented electrically rather than mechanically ? They also change the steering rate as the speed of the car changes, many cars also add four wheel steering which changes from opposition to complement at speed. I am not a mechanic or really a car enthusiast so may be totally wrong.

Anyway in my own car, I still have steering and brakes, but the steering is seriously heavy when the power cuts.

Nissan chose an electrohydraulic power-steering setup in place of some of its competitors' fully electric systems, a best-of-both-worlds solution that provides the feel of a conventional hydraulic setup with the economy benefits of an electric rack. The decision pays dividends the second you start moving -- the steering communicates with the driver, loads up naturally, and suffers from minimal torque steer.

So yes the power steering is not going to work when power is out. I also suspect there is a program to translate the steering wheel turn into power on the electrohydraulic pump, and yes speed sensitive steering so a problem with that program may translate into spurious maneuvers. I was wrong thinking a motor moves the wheels. A pump does that.

Nissan chose an electrohydraulic power-steering setup in place of some of its competitors' fully electric systems, a best-of-both-worlds solution that provides the feel of a conventional hydraulic setup with the economy benefits of an electric rack. The decision pays dividends the second you start moving -- the steering communicates with the driver, loads up naturally, and suffers from minimal torque steer.

So yes the power steering is not going to work when power is out. I also suspect there is a program to translate the steering wheel turn into power on the electrohydraulic pump, and yes speed sensitive steering so a problem with that program may translate into spurious maneuvers. I was wrong thinking a motor moves the wheels. A pump does that.

But more fundementally does that means that a failure of the pump in the Nissan would still allow 'armstrong' direct mechanical steering control for the driver?

Nissan chose an electrohydraulic power-steering setup in place of some of its competitors' fully electric systems, a best-of-both-worlds solution that provides the feel of a conventional hydraulic setup with the economy benefits of an electric rack. The decision pays dividends the second you start moving -- the steering communicates with the driver, loads up naturally, and suffers from minimal torque steer.

So yes the power steering is not going to work when power is out. I also suspect there is a program to translate the steering wheel turn into power on the electrohydraulic pump, and yes speed sensitive steering so a problem with that program may translate into spurious maneuvers. I was wrong thinking a motor moves the wheels. A pump does that.

But more fundementally does that means that a failure of the pump in the Nissan would still allow 'armstrong' direct mechanical steering control for the driver?

Lefty

I'm no mechanic but I doubt you can still turn because I think the pump is not mechanically attached to the wheel. The "other" cars mentioned in the internet blurb must be using electric motors instead of pumps to turn the wheel. That means you have to reach under your hood to spin that motor's rotor if you want to turn the wheels.

Nissan chose an electrohydraulic power-steering setup in place of some of its competitors' fully electric systems, a best-of-both-worlds solution that provides the feel of a conventional hydraulic setup with the economy benefits of an electric rack. The decision pays dividends the second you start moving -- the steering communicates with the driver, loads up naturally, and suffers from minimal torque steer.

So yes the power steering is not going to work when power is out. I also suspect there is a program to translate the steering wheel turn into power on the electrohydraulic pump, and yes speed sensitive steering so a problem with that program may translate into spurious maneuvers. I was wrong thinking a motor moves the wheels. A pump does that.

But more fundementally does that means that a failure of the pump in the Nissan would still allow 'armstrong' direct mechanical steering control for the driver?

Lefty

I'm no mechanic but I doubt you can still turn because I think the pump is not mechanically attached to the wheel. The "other" cars mentioned in the internet blurb must be using electric motors instead of pumps to turn the wheel. That means you have to reach under your hood to spin that motor's rotor if you want to turn the wheels.

It doesn't sound like you have a good understanding on how even conventional power steering works. A pump's output can never be mechanically attached to anything as it's output is a fluid under pressure routed to something that can turn that fluid pressure back to a mechanical force. Standard power steering uses that method but still allows for manual steering even if the pump fails.

So still looking for a definitive answer with reference to any present consumer car uses true steer by wire only, where there is no driver manual (unassisted) steering available if primary power is lost?

My understanding is very limited. I thought the steering column turns gears that turn the front wheels. The power steering pump gets input from the steering column turning and assists with hydraulics so the driver doesn't have to turn so hard. I will see if the last 25% of my car manual has any details.

My understanding is very limited. I thought the steering column turns gears that turn the front wheels. The power steering pump gets input from the steering column turning and assists with hydraulics so the driver doesn't have to turn so hard. I will see if the last 25% of my car manual has any details.

Yes, that is how it works, and steering is still possible with the loss of hydraulic pressure, abet with much more steering force required. So just changing from a belt driven pump to a electric powered pump doesn't change anything significant. Nor would just having an electric motor geared to the steering rack and pinion change the basic concept. But a true steer-by-wire-only would have no pumps, just a motor driving the steering rack and pinion directly and there would be no mechanical connection from the steering wheel to the steering rack and pinion. Does such a steer-by-wire system actually exist in any present consumer auto, that is my question? A poster here said there is, another said several, a couple of us said REALLY!!!, not for me.

Just looking for source references to such a true steer by wire auto.

EDIT: Found this on wiki, seems true steer by wire only is not presently avalible but is often confused with electric powered steering.

Quote

Steer by wire

This is currently used in electric forklifts and stockpickers and some tractors.[1] Its implementation in road vehicles is limited by concerns over reliability although it has been demonstrated in several concept vehicles such as ThyssenKrupp Presta Steering's Mercedes-Benz Unimog, General Motors' Hy-wire and Sequel and the Mazda Ryuga. A rear wheel SbW system by Delphi called Quadrasteer is used on some pickup trucks but has had limited commercial success.This is not to be confused with Electric Power Steering.

Coming back to te original topic, how about three cheers for this SIM900 coming all the way from Taiwan, and having experienced nearly three weeks of happiness in US customs along the way. I wider where they store all the WIP at their rte of processing stuff.

Anyhow, on the GPRS board it goes if I find the time tonight. Note the classy 'antistatic' storage device. Hope it'll still work!

My understanding is very limited. I thought the steering column turns gears that turn the front wheels. The power steering pump gets input from the steering column turning and assists with hydraulics so the driver doesn't have to turn so hard. I will see if the last 25% of my car manual has any details.

Actually, you turn the wheels. XD

The steering wheel is attached to the steering column which has a pinion gear on the end which moves the rack (we're talking rack and pinion here). The rack pushes and pulls the spindles via the tie rod ends. Power steering simply boosts this and makes it easier. Electronic rack and pinion uses electric motors in the unit to help. Some use an electric pump to run a hydraulic boost system.

A couple of joints are in there also to help ensure that the steering wheel does not spear you during a frontal impact. I.e. the Steering system is designed to collapse inside the front (typically motor) space of the car instead of allowing itself to be pushed into the occupied space as the front axle moves backward during impact. Apparently lots of people in the past were speared by the steering wheel, hence the need for seat belts and the development of air bags.

Did you find a good deal at an overseas location? Where and how much did it cost?

A better way to put it was that I was able to find the chip at all. No US distributor I looked at carried it. Not Digikey, Newark, or Mouser. So I E-bay'ed it from Taiwan for about $20. Are you aware of SimCom distributors in the US that sell to civilians?